The present invention relates to an optical cable, or optical fiber cable, of the type described in AEG-KABEL Mitteilungen [AEG Cable Reports], No. 1/82, pages 2-4. Such a cable is composed of a plurality of basic elements arranged in a common sheath, each basic element including a stable sheath and at least one optical fiber loosely guided in the stable sheath. A plurality of such basic elements is combined into a basic unit held together by mounting elements.
In known cables of this type, the basic units are composed of a plurality of basic elements which are twisted around a supporting element. Each basic element includes a stable sheath in which one or a plurality of light conductive fibers are loosely guided so that mechanical stresses on the optical cable can have no adverse effect on the characteristics of the light-conductive fibers. Each basic unit has a cross section which is of stable form. In an optical cable assembled of such basic units in the manner of a unit type cable, there exists a relatively large proportion of unused cavities. therefore the resulting cable diameter is relatively large for the number of fibers present. To fill the cavities with a filler material producing longitudinal water tightness. e.g. petrolatum, a relatively large quantity of material is required.
Multi-fiber optical cables in which individual basic elements are twisted in layers have a smaller diameter and a smaller total space that must be filled, but the costs of manufacturing them are much higher than for the cables of the first-mentioned type.